The Bug Geek

Insects. Doing Science. Other awesome, geeky stuff.

Sometimes poop happens if you’re persistent.

In my last post (thanks, by the way, for welcoming me back into the fold so warmly), I mentioned that I’d spotted a particular butterfly. I was very, very, excited to see this butterfly. You see, I’d been trying to find one of these butterflies for over three years.

Back in March of 2010, I wrote about my encounter with a very evil plant adorned with sharp, woody spines: prickly-ash (Xanthoxylum americanum). It was mostly a complainy post because the plant shredded my dog and made me a little buttsore (literally).  However, Steve Wilson of Blue Jay Barrens mentioned in the comments that prickly-ash is a common host of North America’s largest butterfly, the Giant Swallowtail (Papilio cresphontes). I did some research and learned that I might just be within the butterfly’s typical geographic range.

I’ve been keeping an eye out for that butterfly ever since. (Seriously, I can’t pass a prickly-ash without looking for one).

Well, on that lovely day last week (when I was having all kinds of feels about nature while out with my dogs) my walk came to a screeching halt when I noticed a large black swallowtail butterfly lazily flapping around a patch of prickly-ash in the tree line just to the left of the road.

Now, I wish I’d been able to get a video of this thing, because it moved unlike any butterfly I’d ever seen. Its wingbeats seemed very slow; languid, really.* I wondered how on earth it was keeping its huge body afloat, and nearly in place, to boot. It held itself  vertically as it stopped to inspect various leaves and branches, much in the same posture as a hummingbird that has momentarily stopped drinking at a feeder to hover inches from the nectar before darting down to feed again.

I tiptoed in closer – it didn’t seem bothered in the slightest by my presence. I held my breath as I watched, wondering if…would it? It DID!  She finally found a suitable spot and delicately touched the tip of her curled-under abdomen on a leaf about a foot and a half off the ground, leaving behind a single, round, orange egg.


I came home and chattered to my wife excitedly about my long-desired observation. Then I did some Googling and learned that the caterpillar of the Giant Swallowtail is an exceptional mimic. Like many other caterpillars, P. cresphontes is exceptionally good at looking like something highly unpalatable: poop.  Bird poop, to be precise. How wonderful!

The next day I went back to that little patch of thorniness to see if I could find the egg again: I was thinking it would be cool to keep an eye on its progress. I was able to find it rather quickly:

Egg of Giant Swallowtail caterpillar (Papilio cresphontes)

Egg of Giant Swallowtail (Papilio cresphontes). (Actual size ~1mm)

Satisfied, I stepped back onto the road and took in a broader view of the shrub.

And saw bird poop on a few leaves.

Wait, wut?

I darted in for a closer look and my three-years-of-searching-persistence was rewarded with some absolutely FABULOUS poop-mimicing Giant Swallowtail caterpillars. They are VERY convincing:

Giant Swallowtail caterpillar (Papilio cresphontes) on Prickly-ash Zanthoxylum americanum)

Not actually bird poop.

Giant Swallowtail caterpillar (Papilio cresphontes)

Proof that there is actually a caterpillar under there.

I  removed one of the caterpillars from its leaf and took it home with me for a studio-style shoot (above), but was sure to bring it back to its proper home the next day.  I reached in the little vial holding the critter, picking it up between my thumb and forefinger, and was  immediately reminded that  swallowtail caterpillars often employ another defence mechanism if the “don’t-eat-me-I’m-poop” schtick fails:

Osmeteria of Giant Swallowtail caterpillar (Papilio cresphontes)

“Behold my terrifying red head thingies! Flee if you value your life!”

These osmeteria are hidden away within the thoracic segment behind the head. When threatened, the caterpillar everts them rapidly, simultaneously releasing  a defensive chemical.

I couldn’t help but be reminded of this comic  by the brilliant Rosemary Mosco. The caterpillar’s osmeteria were not very scary. A teensy bit startling perhaps, but honestly, they look like shiny, skinny candy canes.  I noticed the chemical secretion – it had an odour, and not an unpleasant one. I recall it being something a little sweet/spicy. Kind of nice, actually. Maybe it’s revolting if you’re a pecking bird?


*I looked around on YouTube for a good video of this species – there are several – but what struck me was how fast seemed to fly in each of the clips. This was not what I saw at all. I have two explanations: 1) it was  quite chilly that morning (like, I was wishing I had a toque and gloves kind of chilly), which slowed its motions, or 2) this was an example of one of those trippy moments where time seems to slow down.

21 responses to “Sometimes poop happens if you’re persistent.

  1. Sarah September 11, 2013 at 7:52 AM

    I like the idea of time slowing for an entomologist and her butterfly.

  2. Pablo September 11, 2013 at 10:18 AM

    Great article! Greetings from Argentina

  3. Robley September 11, 2013 at 9:53 PM

    Love this post! I just photographed poop-appearing caterpillars myself three days ago, but these photos are far superior to my own. Just loved this.

    • TGIQ September 12, 2013 at 4:40 AM

      We’re all our own worst critics – I’m sure your photos are great 🙂 It seems to be a peak caterpillar-time-of-year right now, but I think these mimics are pretty special – count yourself lucky to have found some! 😀

  4. Lisa Vankula-Donovan September 12, 2013 at 3:28 AM

    Very cool post!!! Loved it. I hope your wife is more interested in your findings than my bothered husband who thinks I’m just a nerd…well, weirdo would be a better word.

  5. Mark Sturtevant September 12, 2013 at 7:30 AM

    This is a coincidence. I too had a similar long-term goal of catching a giant swallowtail. I would regularly see them in the late summer, booking like a bat out of heck through my neighborhood. Never a chance of catch one. Then, a few weeks ago I saw one actually flying slowly like you described. I ran out with my trusty net, and caught it. Showed its beauty to my kids, then let it go.
    Wish I could find prickly ash. Its got to be around here somewhere….

  6. Africa September 12, 2013 at 8:41 AM

    Awesome, what a great comeback! The last photo is fab. This post made my day!

  7. smccann27 September 13, 2013 at 9:27 AM

    Nice! I saw a swallowtail larva like this on one of my weekend jaunts. The poo looked “too perfect” so I investigated more closely.

  8. Chris Grinter September 15, 2013 at 11:29 PM

    I love the crap out of that osmeteria photo!

  9. michaelmarlow September 15, 2013 at 11:52 PM

    The Giants must be coming around; I saw one at the tail end of August, my first ever and a slow-moving beauty at that. It was as you described yours, languidly flying – almost floating – past the living room window. I said…Oh nice, another tiger swallowtail…and went on lazing about. But I soon got called out to the back ( and out I went), because something was on the butterfly bush…Wait a minute you’re not a…tiger…Bing! (Or whatever sound a light bulb going on makes). One of the more nonplussed bugs I’ve come across; I could put my hand/fingers right up to it, and it just kept its beat while feeding on the flowers. I wasn’t even aware they ran through western Mass. Still very happy about it a few weeks later.

    • TGIQ September 16, 2013 at 4:53 AM

      Great story! You’ve almost convinced me that I wasn’t hallucinating about the speed of the butterfly’s flight 😉 It’s definitely a sighting worth long-term happiness 😀

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  11. Scott Hogsten September 17, 2013 at 12:18 AM

    Nice to have you back, I was wondering about you. I almost hate to admit this but during the summer I found several of these caterpillars and was photographing them. I noticed one of them wasn’t moving, that was when I realized it wasn’t a caterpillar.

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